Deterioration of photographic materials happens for many reasons. Mould, heat, humidity, pollutants, cracks and tears, improper storage, insects, chemical decay, air exposure, sunlight and even the oil on our skin. Even with the right measures in place to protect them, all photographs will eventually degrade. Environmental factors, such as heat and humidity, lead photographs to deteriorate more quickly.
Photographic prints stored in a dry environment can roll such as what happened to this one. Andy Nichols photo.
Severely detriorated nitrate negatives from the collections of the Glenbow Archives. Anita Dammer photo.
A positive copy of a acetate negative affected by vinegar syndrome. Canadian Architectural Archives, UCalgary: 28A_78.01_PAN_51436-2.
Cellulose acetate film can suffer from a condition known as “vinegar syndrome.” As acetate film begins to decay, it produces vinegar-smelling acetic gas. This acidic gas prompts the plastic base to become brittle and shrink, causing the image-bearing emulsion layer to delaminate and disfigure the image.
An acetate negative affected by vinegar syndrome. The channels and cracks are caused as the emulsion and the plastic base separate. Simpsons Store, south-west section. Canadian Architectural Archives, UCalgary: 28A_78.01_PAN_51436-2.
Cellulose nitrate film was the first film made with a plastic base. Compared to glass plate negatives, nitrate film was portable and easy to use. But as it decays, it becomes highly flammable and under the right conditions, it can self-combust. Many photographers lost their studios and their negative collections in fires caused by nitrate negatives. A fading image is the first sign of nitrate degradation.
Glass Negatives and Slides
Glass negatives and slides face a unique challenge: While the emulsion layer, which sits on a glass plate, degrades like any other photograph, the glass also becomes more brittle with age. The brittleness leaves this format prone to cracks, chips, and shattering. Environmental changes can cause the emulsion to flake away from the glass support as the glass can‘t expand and contract with the emulsion.
Improper storage and rough handling are the greatest threat to the preservation of photographic prints. Many types of photo albums contain glues or acids that can damage prints. Most people keep photos in boxes and drawers, which can cause cracks or tears. Curled prints are often a sign of low humidity because the emulsion layer and its paper support respond differently to environmental changes.
Rochester Institute of Photography Image Permanence Institute Graphics Atlas: Object-based approach of the identification and characterization of prints and photographs.
Northeast Document Conservation Center nitrate film
A Visual Glossary of Six Stages of Acetate Film Base Deterioration
Glass Negatives and Slides:
The Preservation of Glass Plate Negatives